Destructive hydrogenation of heavy hydrocarbons



`Iuly 10, 1962 M. F. NATHAN ET AL DESTRUCTIVE HYDROGENATION OF' HEAVYHYDROCARBON Filed OCt. 19, 1953 2 Sheets-Shes?l 1 T0 FIG. 2A

(D (D N O g mg u AlR NOGHVD OJ. L'IVHdSV .-iO OIlVH OIL FEEDC T0 PRODUCTRECOVERY SYSTEM sEvERVrY FACTOR INVENTORS MARVIN F. NATHAN EVERETT W.HOWARD HENRY G. Mc GRATH ATTORNEYS July 10, 1962 M. F. NATHAN ETALDESTRUCTIVE HYDROGENATION OF HEAVY HYDROCARBON 2 Sheets-Sheet 2 led OCC.19, 1953 mmDOI M Q INVENTORS MARVIN F. NATHAN EVERETT w.HowARo HENRY G.MacRATH 3,043,769 DESTRUCTIVE HYDRDGENATION OF HEAVY HYDROCARBONS MarvinF. Nathan, New York, N.Y., and Everett W.

Howard, Glen Rock, and Henry G. McGrath, Union, NJ., assignors to The M.W. Kellogg Company, Jersey City, NJ., a corporation of Delaware FiledOct. 19, 1953, Ser. No. 386,758 Claims. (Cl. 208-112) The presentinvention relates to an improved process for cracking under hydrogenpressure, and more particularly, it pertains to a method of crackingheavy or residual oils under hydrogen pressure whereby a minimumproduction of carbon and normally gaseous products is obtained and asuitable feed material for. catalytic operations is produced. i

Residual oils in petroleum refineries are distress stocks in that theyare not very satisfactory as feed materials for cracking operations byreason of metal contamination of the catalyst and the simultaneousundesired production of carbon and normally gaseous products whichrepresents an economic loss. It has been suggested that such materialsbe subjected to a coking operation whereby gasoline and otherproductmaterials are produced, however, this process is not consideredtoo satisfactory for commercial exploitation, because of the pooranti-knock quality of gasoline product and the high yield of carbon. yAnother previously suggested technique involves conventional catalyticcracking of this material, however, this method is not entirelysatisfactory because of the high carbon yields and the adverse effect ofthe feed stock on catalyst life. It has also been proposed that residualoils be cracked under hydrogen pressure in order to overcome some of the`disadvantages enumerated above, and itwas found that while this processhad advantages, the results were not suicient to justify commercialapplication.

Upon further investigation, it was discovered that prior workers wereemphasizing factors in theY method of cracking under hydrogen pressurewhich did ,not serve for the best eiciency nor economical interest.` Forexample, prior workers emphasized in their work the use of operatingconditions which would produce a maximum yield of gasoline.A Invariably,this method of operation results in converting an uneconornicalquant-ity of feed material to carbon and normally gaseous products andin producing a grade of gasoline which is not as good as the productfrom a catalytic cracking operation. By extensive investigation, it wasldiscovered by use, that cracking under hydrogen pressure should beoperated under mild conditions to produce little or` no gasoline suchthat a small amount of feed material is converted to carbon and gas,`and an excellent feed stock `for catalytic cracking is produced. v Byoperating in this manner, the amount of gasoline produced is small;however, this is an advantage, because cracking under hydrogen pressureis an expensive way of making gasoline, and any gasoline made mayrequire further processing to improvethe quality thereof. By means ofthe present invention, Ithe final gasoline product is made by theefficient and economical method of conventional catalytic cracking. p

An object of this invention is to provide an improved method forcracking residual oils under hydrogen pressure.

Another object of this invention is to provide a co-mbination process inwhich residual oil is cracked under hydrogen pressure to producev a feedstock for a catalytic cracking operation.

Still another object of this invention is to crack residual oils underhydrogen pressure to produce a high yield vUnited States Patent OPatented July 10, 1962 of feed stock vfor catalytic cracking operationsand a low yield of carbon and normally gaseous products.

Other objects and advantages of this invention will *become apparenttrom the following description and explanation thereof.

By means of the present invention, a residual oil is cracked underhydrogen pressure inthe presence of a suitablecatalyst and undercracking conditions including a severity factor of not more than about0.50. The severity factor is defined hereunder as the quotientrofdividing the catalyst to oil ratio by the volumetric space velocity.

The catalyst to oil ratio in this invention is the volumetric ratio ofcatalyst to oil, on an hourly basis. Ordinarily, the `catalyst to oilratio is used only to `describe an operating condition in moving uidybed systems, however, for the purposes of this specification and theappended claims, a superficial catalyst to oil ratio is also used for afixed bed system, and it is determinedby taking the reciprocal of theproduct of the reaction period or cycle in hours and the volumetricspace velocity.

The best application of this invention is to utilize as lfeed stock amaterial which is commercially unattractive for any of the gasolineproducing processes, for example, catalytic cracking, thermal cracking,vacuum distillation, etc. Generally, such a material has an API gravityof up to about 20, however, this `invention has particular applicability`for processing feed stocks having'an API gravity of from about l toabout 13; and which has an unusually high carbon residue, generally,more than -about 0.6% by weight, more usually, about 5 to 30% by weight.

, Another method of indicating this characteristic of the feed materialis the asphalt content, and it can be from 'about -2 to 60% by weight,more usually about 15 to 50%. in refining practice, the crude oil isseparated into several fractions, one of which constitutes the feedstock for conventional catalytic cracking, and it has an end point inthe range of about 850 to about l025 F. The higher boiling fraction isthe residual oil, and it has an initial boiling point which varies withthe end point of the feed material vfor the conventional crackingoperation. This residual oil has ia high yco-king tendency by reason ofthe high molecular weight compounds it contains and the asphaltic natureof them. Another characteristic of the `feed stock for this invention isthe sulfurcontent, which is usually higher than any other fractionsseparated from the crude oil. Inthe case of Mid-Continent crudes, thesulfur content is relatively low as compared to ,West Texas crudes, andfor the purpose of this invention, the sulfur content is at least about0.1% by weight, more usuallly, about 0.5 to 6% by Weight. Specificexamples of residual oils for use in this invention are reduced crudesrepresenting up to about 40% of the ltotal crude, more usually, not morethan about 25% on a volumetric basis; although the best application ofthis invention is with regard to, for example, vacuum tar; thermalcracking tar; fuel oil; etc. It should be understood, however, that inthe case of very heavy, crude oils, the reduced crude may represent -upto about 70 to 80% of the entige material and therefore, the gravity ofthe reduced cru-de is the controlling feature. Y

l The residual oil is subjected under reaction conditions to atemperature which is suitable for effecting mild cracking reactions. Thepurpose is to convert residual oil compounds to catalytic cracking feedstock or gas oil with a relatively small production of gas, gasolineand.`

the desired products. The feed stock to he used for conventionalcatalytic cracking is considered as having an By means of the conditionsemployedA fraction or product. The temperature at which cracking underhydrogen pressure is effected lies between about 675 and about 925 F.,preferably about 750 to about 875 F. Higher temperatures tend to producenormally gaseous lproducts vat a faster rate than is desired, hence,

they vare not'preferred; whereas lower tempertaures thanl the minimumgiven Vabove may result in an undesirably slow -rate ofV reaction. v Thetotal reaction pressure is selected primarily on the basis of providinga desired hydrogen partial pressure. Accordingly, the pressure variesfromabout 50jto about 2500 p.s.i.g., more usually, about 500 to about1500 p.s.i.g. With regard to reaction pressure, it should be noted thata substantial part of the feed stock may tend to exist inthe liquidstate under reaction conditions. It is preferred, however, for a fixedbed` system, to effect the reaction in the liquid phase or inamixedphase of vapor and liquid. lIn the xed bed operationfa non-fluidycatalyst is employed by reason that a substantial amount of reactantscan exist in the liquidstate under reaction conditions. Such a mode ofoperationmakes possible the production of large quanti- Vties ofa heavyproduct fraction or asphalt boiling in essentially the saine range asythe residual oil feed, and

thisasphalt product has an API gravity `falling within the rangespeciedabove for the residual oil feed. It should be understood that thepresent invention can be practiced asa fluid system, employing eitherthe xed or moving bed technique; In a Vsevere operation, the quantity ofsuch heavy product material may not be more than about by volume of thefeed; whereas in the practice of this invention, the .yield of thismaterial is usually at least about-35% or at least 45% and up to about70% asphalt fraction which boils above thel feed stock for thevconventional catalytic cracking operation can be recycled to thereaction zone until all or part of the material is converted to lowerboiling products and/ or carbon. The recycle ratio, measured as parts byweight of product boiling above the catalytic cracking `feed stock toparts by Weight of residual oil feed, on the same time basis, is about0.1 to 5, more usually, about 0:25,'to 2. Itis intended that'all or partof the highest boiling product fraction be recycledfto the reactionzone.

The reaction is conducted under hydrogen .pressure in order to minimizecarbon formation, lproduce a product of high .saturation and containinga fraction having good characteristics as feed stockl for 'catalyticcracking operations and a fraction which is not very refractory forre-processing, etc. To effect this purpose, hydrogen the standard cubicfeet 60 `F. and 760 mm.) per barrel of feed (l barrel is equal to 42gallons), s.c.f.b., and it can` vary fromY about 500 to about 50,000s.c.f.b., more usually, about 2500 to about 30,000 s,c.f.b.

The rate of charging residual oil to the reaction zone is measured on arelative basis to the volume of catalyst which is present therein( Thisis termed as the volumetric space velocity, and it is measured as thecubic feet of liquid feed charged to the reaction Zone on an hourlybasis per cubic foot of catalyst present therein. The volumetric spacevelocity is an vimportant factor for measuring severity, although, inthe present case, by it- Thev includes the recycle oilrate. Y p

Since the present invention can be operated as a fixed 4I y i bedsystem, a superficial catalyst to oil ratio, on a volumetric basis, isemployed for indicating severity. This superficial catalyst to oil ratiois calculated as the reciprocal of the product of the reaction period inhours and the volumetric space velocity. The reaction period isimportant, because in a fixed bed system, the activity of the catalystdeclines with use, consequently, the longer vthe reaction period, thelower the catalyst activity. The

importance of the volumetricspace velocity was de-Y scri-bed above. Inthe practiceof this invention, the catalyst to oil ratio (to beunderstood as including the superficial and actual catalyst to oilratio) varies from about .001 to 4,.more usually, about 0.1 to l. Thereaction period is also important, and it can vary from about 0.5 to 200hours, more usually, about 2 to 150 hours. The required severity forlthe operation of our process is best determined by means of theseverity factor, which is calculated in accordance with the followingequation: Y

' T`represents the reaction period in hours and V.S.V.

is the volumetric space velocity (VO/hL/Vc). To produce the effectsdesired in this invention, the vseverity factor is not greater thanabout 0.50, more usually, about 0.05 to 0.5. It is shown hereinafterthat by operating withinthe defined severity factor, theratio of asphalt(product boiling above fraction used as feed for catalytic cracking) tocarbon is very satisfactory for commercial use. The carbon yield isproportional to the normally gaseous product yield, hence, if thecarbonyield. in: creases, there is a similar effect in the gas yield.Further, by operating within the severity range of this invention, theyield of gasoline and furnace yoil is substantially lower than isobtainedby conventional methods of operation. There is a break point inthe relative yields of the various products and this is best illustratedby the ratio of the asphalt product yield to the carbon yield. As theasphalt yield increases, the yields of carbon, gas, gasolinev andfurnace oil decreases, whereas the yield of gas oil which is to serve ascatalytic cracking feed stock declines relatively little. Since thecarbon represents an economic loss, the efficiency of operation for thepurposes of this invention can be measured as the ratio 'of asphaltproduct to carbon. The greater the yield of asphalt, the smaller theloss of feed as carbon and normally gaseous material and since the gasoil yield varies relatively little, the conditions are chosen to producelarge quantities of asphalt for subsequent recycle. Cracking lighterproduct fractions than residual oil under hydrogen pressure to producegasoline is much more expensive than by conventional catalytic cracking.One reason for first treat-l ing the residual oil by means of thisinvention before charging the gas oil fraction or product toconventional catalytic cracking, is to avoid the great harm which isdone toy catalyst activity by the residual oil in conventionaloperations. Hydrogen pressure suppresses Vsuch effects to a significantextent, consequently, the present process is advantageous from thisstandpoint. Further, the coke yield-in conventional cracking of residualoils is greater than in the method of this invention, because hydrogenpressure suppresses coke formation.

The main aspect of this invention is concerned with cracking underhydrogen pressure to produce feedstock for conventional catalyticcracking. lA suitable feed stock for conventional catalytic crackingdoes not contain more than about 0.6% carbon residue, otherwise theremay be serious' adverse effects on catalyst activity. Anotherdisadvantage in using residual oils containing more than about 0.6%carbon residue is the excessive coke production. Accordingly, in thepractice of this invention, gas oil product to be used as feed forcatalytic cracking operations should contain not more than the optimumamount of carbon residue. At present, this value is 0.6% by Weightcarbon residue, however, in the event that improvements in catalyticcracking permit the use of higher carbon residue in the feed, then it isintendedy to adjust the operation of this invention in order to providea higher limit of carbon residue.

As a result of cracking under hydrogen pressure, the catalyst becomescontaminated with carbon or carbonaceous material which lowers theactivity temporarily. The catalyst activity can be revived by burningthe carbonaceous deposit with an oxygen containing gas, c g., air,oxygen, diluted air containing 2 to 15% of oxygen by volume, etc., at #atemperature of about 600 to 1250 F., more usually, about 950 to about1200 F. The regeneration can be conducted at atmospheric pressure or atsuperatmospheric pressure as within the range mentioned above for thereaction. The quantity of oxygen containing gas used and the length ofregeneration cycle depend fupon the carbonaceous 'content of thecatalyst. Generally, in a xed bed system, the regeneration cycle isabout 0.5 to about 50 hours, more usually, about 2 to 24 hours.Following the reaction cycle, the catalyst in the processing zone can bedepressured; purged With inert g-as such as, for example, steam, fluegas, carbon dioxide, nitrogen, etc.; and then subjected to regenerationtreatment. Following regeneration, in lsome cases, it is desirable toprecondition the catalyst with a hydrogen containing gas. This isparticularly true of the dehydrogenation-hydrogenation types ofcatalysts.

The catalyst employed in this process is one which can possess crackingactivity to a small extent, or this catalyst property can be predominantin conventional cracking catalysts. Generally, for the purposes of thisspecication and the appended claims, la cracking catalyst is one whichposesses activity for cracking reactions to the extent suited for thepresent invention, and this can be at least about 5 or about 10% of thecracking activity possessed by a conventional silica-alumina crackingcatalyst having a D-i-L activity of `about 45. The various types orgroups of catalyst :are many, including the silica containing crackingcatalysts in which the silica varies from about 0.5 to 100% of the totalcatalyst, on a. weight basis. In the type of catalyst used forconventional cracking, the silica content varies from about to about 95%by weight of the total catalyst. Examples of silica containing catalystsare silica-alumina, silica-magnesia, silica gel, pumice, kieselguhr,fullers earth, silica-zirconia, silicaboria, etc. Another group ofcatalysts are the alumina containing catalysts in which the aluminacontent varies from about 0.1 to about 100% by weight of the totalcatalyst. Examples ci these catalysts are alumina gel or activatedalumina, alumina-magnesia, alumina-boria, bauxite, Super-Filtrol, clays,etc. Another group of catalysts are those which are better known fortheir hydrogenation and/ or dehydrogenation properties, including thecompounds of elements of groups V and VI of the periodic table, notablythe lleft hand elements of group VI in the form of the oxide and/orsultide. These catalysts can be combined with compounds of group VIIImetals having an atomic number not greater than 28, particularly theoxides and/ or suliides of these metals. Examples of catalysts comingwithin the definition of this latter group are molybdenum oxide-alumina,chromium oxide-alumina, tungsten oxideaalumina, tungsten oxide-nickeloxide-alumina, vanadium oxide-alumina, cobalt molybdate-alumina,tungsten sulfide-nickel suliide-alumina, molybdenum sulfide-nickelsulfide-alumina, nickel on alumina, etc. 'I'he catalytic elementconstitutes about 0.1 to about 25% by weight of the total catalyst, andthe carrier material can be materials other than 'alumina such as, riorexample, silica, silica-alumina, silica-magnesia, zinc spinel, bauxite,Super-Filtrol, etc.

Conventional catalytic cracking is familiar to those skilled in the art,and it includes such known processes as fluid catalytic cracking,Houdriow or the Houdry proca to a vacuum ashing or distillation unit.

ess, Thermofor catalytic cracking, Cycloversion, etc. These processesinclude moving and fixed beds using a iluid or non-fluid technique.Generally, a temperature of about 800 to about 1025 F. is used, moreusually, 900 to yabout 1000 F., and the pressure varies from about oneatmosphere to about 100 p.s.i.g. The weight space velocity, measured asthe pounds per hour of liquid feed charged to the reaction zone perpound of lcatalyst present therein, varie-s from about 0.05 to l0, moreusually, about 0.1 to :about 3.0. In a moving hed system, the catalystto oil ratio, on a weight basis, varied from about 0.5 to 20, moreusually, about 2 to 10. The catalyst employed usually comprises thesilica containing type, and it contains about l5 tol about 100% silica.EX- amples of catalysts are silica gel, bauxite, Super-Filtrol,bentonite and montmorillonite clays, synthetic silica-alumina,silica-boria, silica-magnesia, silica-zirconia, etc. The silica-aluminacontaining catalysts lare used extensively, and they contain about 15 toabout 95% silica, based on the total weight of catalysts.

In another #aspect of this invention, the total crude is firstfractionated under atmospheric pressure to separate various straight runfractions as gasoline, naphtha, kerosene, gas oil, :reduced crude, etc.The gas oil, all or part is utilized as diesel oil or ias feed to aconventional catalytic cracking unit for the production of gasoline. TheC3 land C4 unsaturated hydrocarbons produced in the catalytic crackingiunit are charged to a catalytic polymerization unit, such as one usingcopper pyrophosphate or phosphoric acid as catalyst, to produceadditional quantities of gasoline. The straight run naphtha is chargedto a hydroforming unit which utilizes molybdenum oxide orchromia-alumina catalyst or platinum on alumina. The

system is operated to effect a net production of hydrogen in 4a mannerwell-known to those skilled in the art, and

.it is a particular advantage in this inrvention to use the net hydrogenproduced as feed in the cracking under hydrogen pressure operation. Thisis particular-ly true for Hydroformers using platinum catalysts, becausethe normally gaseous product contains about 90% hydrogen by volume. Thereduced crude fraction comprising about 20 to about 60% by volume of thetotal crude is charged The overhead distillate from the vacuum unit ischarged to the conventional catalytic cracking unit for gasolineproduction. The bottom fraction comprises about 5 to 25% by volume ofthe total crude and has an API gravity of about 1 to 13. This very heavyfraction is charged to the cracking under hydrogen pressure unit orhydrocracking unit for the production of feed stock for the conventionalcatalytic cracking unit, in accordance with the method of the presentinvention. The normally gaseous product from the hydrocracking unit ischarged to fthe catalytic polymer'ization unit disclosed above. Thenormally liquid product from thek hydrocracking unit can be chargeddirectly to the atmospheric topping unit wherein straight run fractions`are separated from the total crude for similar treatment. Fllhe feedstock for conventional cracking, produced in the hydrocracking unit,along with the asphalt product is processed through the vacuum flashingunit. A small part of the asphalt product, constituting about l to 15 byvolume of thetotal asphalt product, can be withdrawn from the reactorsas a fuel oil product. 'I'he recycled asphalt product and straight runvacuum tar `are charged to the hydrocracking unit. Alternatively, thenormally liquid product from the hydrocracking unit can be preliminarilytreated to eect a separation of asphalt product under atmophericpressure conditions, and this asphalt product is charged to the 'vacuumflashing unit to insure complete separation of the feed stock forconventional cracking or gas oil from the asphalt material.Alternatively, Iall or part of the straight run kerosene, without orwith all or part of the cycleoil fraction from the conventionalcatalytic cracking unit can be charged to a thermal cracking unit foradditional production of gasoline. The processes or units discussedabove are well-known to those skilled in the "art, hence, there is noneed to discuss them herein with any degree of particularity. In theevent that .the quantity of hydrogen supplied to the hydrocracker fromthe hydroformer unit is not sufficient for hydrocracking needs, it iscontemplated using a hydrogen unit involving reforming of methane orrenery gas with steam vand the water gas shift reaction with steam.

For the purpose of evaluating this invention, a feed stock comprisingvacuum tar, having the properties given below in Table. I was processedin accordance with the conditions given in Table II. The resultsobtained are yalso reported in Table II. The catalyst used in these rimscomprised 7.3% tungsten oxide, 2.7% nickel oxide and the remainderalumina, on a weight basis.

Table l API gravity 5.8 Viscosity, SUV, 130 F. 10346 Color, ASTM S-l-DSulfur, wt. percent 5.45 Carbon residue, percent 19.8

Table II Bun No 1 2 3 4 5 Temperature, F 810 840 803 836 794 Pressure,p.s.i.g l, 000 1, 000 1, 000 1,000 Space Velocity, Vol. 0.60 0.68 1. 450.68 Reaction Period, Hrs 4 4 4 4 24 H2 rate, 5.0.1.1) 18, 000 24. 00018, 000 8,000 19, 000 Severity Factor 2. 6 0. 7 0. 47 0.12 0.09 Yields(Basis Feed):

Gasoline, IEP-410 F.,

Vol. Percent 27.0 23.0 12. 10.0 6.0 Furnace Oil, 410-670" V01. Percent41.4 32. 0 19. 3 17. 0 12.5 Gas Oil, G70-950 F.,

Vol. Percent 27.3 24. 0 21.1 21. O 20.0 Asphalt, 950 F., Vol.

Percent 4. 1 21.0 47. 7 54. 0 61.4 Carbon, Wt. Percent 6. 4 3. 5 2. 4 1.4 0.6 Dry Gas,1 Wt. Percent-. 6.4 5.2 1. 5 1.8 0.9 Sulfur eliminated,Wt.

Percent 5. 1 4. 5 3. 8 2. 7 2. 5

1 Cl-C; hydrocarbons.

From the data presented in 'Fable II, it can be seen that the yield ofgas oil does not vary appreciably with different severity of operationconditions, but the quantity of asphalt varies widely. As the asphaltyield increases, the quantities of gasoline, furnace oil, carbon and drygas decrease, hence, this product can serve as a means of indicating theseverity of an operation. Since the carbon and dry gas represent aneconomic loss in the process, it is desirable to operate the presentinvention within the range Idellined by a sharp break in the ratio ofasphalt to carbon. In this regard, a correlation of these two factors isgiven in FIGURE 1 of the `attached drawings, and it is noted therefromthat the present invention should be operated with a severity factor notgreater than about 0.5. Operations in which the severity factor is lessthan 0.5 result in la relatively high production of asphalt, however,the carbon, dry gas, gasoline yand furnace oil yields rare low. Theasphalt can he recycled in any quantity desired to produce additionalquanti-ties of gas oil at a low crate of carbon and dry gas production.

l In FIGURE 2 of the attached drawings, a schematic drawing of apreferred method of practicing the present invention is given.

` In FIGURES 2 and 2A, oil feed having an API gravity of 5.40 isintroduced through line 5 at the rate of 7960 b.p.s.d. and atatemperature of 750 F. This oil charge is comprised of 17% Kuwait reducedcrude plus recycle asphalt oil in an amount to provide a recycle ratioof about 1.1321. The reaction system consists of six reactors, A, B, C,D, E and F,'respective1y. At any given time, two of the reactors are onreaction cycle, consequently, in this embodiment, the oil feed passesfrom line S through line 7, containing 'a valve 9 in an open position,and thence, it enters reactor A through a header 10 depending therefrom;and it also flows through a line 11 containing va valve 13 in an openposition, and thence enters reactor D through depending header 14. Eachof the six reactors contain approximately 642 cubic feet of catalystconsisting of 2.7% nickel oxide, 7.3% tungsten oxide on ialuminasupport. An average reaction temperature of about 825 F. is maintainedduring the reaction cycle at a total pressure of albout 900 p.s.i.g. Inthis example, the oil' feed passes upwardly through the catalyst bed,however, it should be understood that the system can operate eectivelyas 1a downflow reaction system. The quantity `of oil being charged toeach reactor relative to the volume of catalyst situated thereinprovides a volumetric space velocity of about 1.45 Vo/hL/Vc. Eachreactor has a reaction cycle of four hours, therefore, the superficialcatalyst to oil ratio is 0.17. Cracking of the residual oil is effectedin the presence of hydrogen which is supplied through a line 16.Hydrogen containing gas enters reactor A through a line 17, whichcontains a Valve 19 in :an open position, 'and thence it passes throughheader 10 which is connected to the bottom of the reactor. In la similarmanner, hydrogen is supplied to reactor D from line 16 through a secondline 20 containing an open valve 22. The hydrogen rate to reactor D issubstantially the same as the rate being charged to reactor A and thecombined rate is 8000 s.'c.f.b. At the appropriate time in :the completecycle of operation, reiactors B, C, E and F will also have oil andhydrogen containing gas fed thereto in 1a manner similar to what hasbeen described for reactors A and D. In the case of reactor B, the oilwill pass through the line 23 containing valve 24 and hydrogen ischarged thereto through line 26 containing valve 27. In the case ofreactor C, the oil feed ils charged through line 29 containing valve 30and the hydrogen for the reaction cycle is supplied through line 32containing valve 33. For reactor E, the oil is charged through line 35containing valve 36 and the hydrogen for the reaction cycle is `suppliedthrough line 38 containing Valve y39. For the end reactor F, the oilfeed is charged through line 41 containing Valve 42 and the `hydrogen tobe used with the oil feed is supplied through line 44 containing valve45. The oil feed lines leading to reactors A, B, C, D, E, and F irstpass through headers 47,48, 49, 50, 51, and 52, respectively, prior toentering header 10 of reactor A, header 54 of reactor B, header 55 ofreactor C, header 14 of reactor D, header 56 of reactor E Iand header 57of reactor F. The hydrogen containing gas first passes through headers60, 61, 62, 63, 64, land 65 of reactors A, B, C, D, E and F,respectively, prior to entering the appropriate headers thereto. Byvirtue of the superficial catalyst to oil ratio and the volumetric spacevelocity thereof during the reaction cycle, a severity factor of 0.12 isobtained.

The reaction product leaves reactor A through header 67 before passingthrough a line 68 containing an open valve 69. The reaction productflows from line 68 into a common header 70, and thenceI it passes to asystem providing a preliminary separation of normally gaseous productmaterial from the normally liquid products. Reactor D, Which is also onreaction cycle, has the reaction product discharged from the header 72into line 73 wntaining valve 74 in an open position, before flowing intocommon heeader 70. Similarly, when reactors B, C, `E and F 'are onreaction cycle, the reaction product flows iirst through headers 76, 77,78 `and 79, respectively, and f thence through lines 81, 82, 83 and S4containing valves 36, 87, 38 and 89, respectively, before enteringcommon header 70. The reaction product is at `a temperature of about 845F. It was indicated hereinabove, that the oil feed is preheated to atemperature of about 750 F. The temperature of the reaction product is'attained byreason of the temperature at which the hydrogen containinggas is supplied to the reaction zone. In this example, the temperatureof the hydrogen containing gas` is 880 F.

andby virtue of the quantity at which it is supplied to the reactionzone, a resultant average reaction temperature of 'about 835 F. ismaintained.

The reaction product owing through common header 70 is first cooledindirectly in heat exchanger 91 to a temperature of Iabout 610 F. beforeentering a second heat exchanger'92 via line 93 in which the temperatureis reduced to about 450 F. The cooled reaction product leaves exchanger92 yand flows to a condenser 94 via line 95, By means of condenser 94,the temperature of the reaction product is reduced to about 110 F. Thecooled reaction product flows from the condenser 94 to -a flash drum 97by means of line 98. In ash drum 97, the pressure is maintained at 880p.s.i.a., which is essentially the same as the reaction pressure.Normally gaseous product materials are Withdrawn overhead from flashdrum 97 through line 100. A depending portion 102 of ash drum 97provides for the removal of liquid water therefrom by means o-f a valvedline 103 connected to the bottom end of this portion. The normallyliquid product material at .the pressure in flash drum 97 is withdrawnfrom the bottom thereof through a line 105, and thence it is passed to alow pressure ilash drum 107 The pressure in the low pressure flash `drumis 65 p.s.i.a., and the temperature is approximately 100 F. The ashmaterial is withdrawn overhead through line 109; whereas the liquidproduct is removed from the bottom of ash drum 107 via line 110. Theliquid product in line 110 passes through heat exchanger 91 wherein -itis heated indirectly by means of the reaction product flowing from`common header 70, previously described. The liquid product is heated toa temperature of about 540 F prior to leaving heat exchanger 91 through.line 111, and thence, it is passed to the product recovery system. Inthis example, it is contemplated charging the liquid product from line111 to an atmospheric topping tower wherein `any gasoline, furnace oiland gas oil are separated for processing in other types of systems, forexample, the gas o-il product is charged to a fluid catalytic crackingoperation which is operated at a temperature of about 950 F., a pressureof about p.s.i.g., a catalyst to oil ratio of about 8, utilizing asynthetic silica-alumina catalyst containing 85% of silica, and a weightspace velocity of about 1. The total liquid product being charged .tothe atmospheric topping tower (not shown) has an API gravity of 16.2,and it is produced at the rate of about 14,100 gallons per hour. Thetotal crude oil is charged to the topping tower, hence, the asphaltproduct from the present operation is combined with reduced crudecomprising 17% by volume thereof. By reason of the incomplete separationof gas oil from the heavy tar in the topping tower, the crude productstream comprising predominantly asphalt and reduced crude is charged toa vacuum distillation tower wherein a sharp separation is elected `forthe separation of tar and :asphalt from gas oil, the former materialconstituting the feed for the reaction system under consideration.

The normally gaseous product material yielded overhead from highpressure llash drum 97 through line 100 is charged into a surgedrum 115.Make-up hydrogen at the rate of 2,160,000standard cubic feet per hour(measured at 60 F. and 760 mm.) is ycharged to the surge drum 115 bymeans of line 116. Any liquid appearing in the surge drum is dischargedfrom the bottom end of the surge drum by means of valved line 117. Thenormally gaseous product material referred to vhereinafter as. .therecycle gas, combined with the make-up hydrogen, is discharged overheadfrom surge drum 115 lby means of line 118, and thence it is compressedto a pressure level of 965 p.s.i.g. in compressor 119. The compressedgas is discharged Ifrom compressor 119 through line 120, *and thisstream divides into iines 121 and 122, which in turn are connectedto'coils 123 and 124, respectively, .in furnace -125- The heated gas -isdischarged from coils 123 10 and 124 and passed into lines 126 and 127,respectively, and these lines combine as supply line 16.

The heat contained in the reaction product is partly utilized for theproduction of steam. In this regard, water is supplied through a line130 lat the rate of 33,500 pounds per hour, and it is transported bymeans of pump 131 and line 132 into the bottom part of boiler 134. 1677pounds per hour of Water are removed from boiler 134 through a valvedline 136 in order to prevent an accumulation of undesirable material inthe boiler. Water is withdrawn from the bottom side of one end of theboiler 134 through a line 138, which in'turn is connected to heatexchanger 92 in whichy the heat content ot the reaction product isutilized for the production of steam. A mixture of steam and heatedwater is discharged `from exchanger 92, and it passes into a line 139which is connected to the top part of boiler 134. The steam manufacturedby this method is discharged from the boiler via valved line 140 at therate of 31,873 pounds per hour. A portion of the steam manufactured inthis manner is utilized for purging the reac-4 tion system. Steam ischarged at the rate of 2000 pounds per hour `for purging ythrough line142. Steam purging of the reactors is effected after the reaction Vesselhas been depressured. This purging cycle is conducted over a 20 minuteperiod prior to' commencing downflow regeneration. the reactors A, B, C,D, E vand F, steam is admitted into line 144 containing Valve 145, line146 containing Valve 147, line 148 containing valve 149, line 150containing valve 151, line 152 containing valve 153 and line 154containing valve 155, respectively. The steam is vented from reactors A,B, C, D, E and F by means of a line 157 containing valve 15S, line 159containing valve 160, line 161 containing valve 162, line 163 containingvalve 164, line 165 containing valve 166 and line 167 containing valve168, respectively. Lines 157, 159, 161, 163i, 165 and ,167 are connectedto a header 170 from which the l steam used for purging is exhaustedfrom the system.

The air supplied for the regeneration of the catalyst is admittedthrough 4line 172, and it is `com-pressed in compressor '173 to apressure of 110 p.s.i.g. The air is sup plied at the rate of 24,600pounds per hour. The compressed air is discharged from compressor 173 toa line 174, and it enters the top end of a surge drum 175. Any liquidwhich is formed during the compression stage is separated from the airstream, and it collects in surge drum 175. This condensate is removedfrom the surge drum 175 via line 176. The `compressed air is dischargedfrom surge drum 175 through a line 177. Cooled recycle flue gas iscombined with air in line 177 by means of line 178. The .ilue ygas isrecycled at the rate of 209,000 pounds per hour, and it has atemperature of 850 F. In this particular example, the mixture of lluegas and air at 800 F. ows upwardly from line v177 into line 180.Reactors B and C are undergoing regeneration by the downtlow technique.rThe maximum temperature of regeneration is 1150 F, Accordingly, theregenera-l tion gas passes fromline 180 into line 182 containing valve181, and thence into header 76 of reactor B. The regeneration gas alsopasses through line 183 containing valve 184 and thence, into header 77of reactor C. At appropriate intervals reactors A, D, E and F undergodowniiow regeneration by the passage of regeneration gas through line185 containing valve 186, line 187 containing valve 188, line 189containing valve 190 and line 191 containing valve 192, respectively. Inthe case of reactors 1B and C, the tue gas resulting from downflowregeneration passes through headers 54 and 55 of these reactors, and inturn, the ue gas flows through line 195 containing valve 196 of reactorB and line 197 containing valve 198 of reactor C. 'I'he flue gas isthenV passed from lines and 197 into a header 200. A portion of the flue`gas ows into line 201 in order that it can be cooled for the purpose ofrecycle; whereas the remainder is vented from the system through a line202. In the.

When steam purging is under Way each of event that reactors, A, D, F.and F undergo downflow regeneration, the iiue gas enters header 200 bymeans of line 204 containinglvalve S, line 206 containing Valve 207,line 208 containing Valve 209 and line 210 containing valve 211,respectively.

vIn. the case of upiow regeneration, the regeneration gaspassing throughlines'177 and 178 enters a main header 213. For reactors \A,V B, C, D, Eand F, the regeneration gas being supplied through line r213 `canpassthrough line 214 containing valve y215, line216 containing valve217, line 218 containing valve 219, line 220 containing valve 221, line222 containing valve 223 and yline 224 containing valve 2215,respectively. The upflow regeneration iseffected at a temperature of1150F. and a pressureof 110 p.s.i.g.. The flue gas resulting yfrom upflowregeneration is discharged from the reactors A, iB, C. D,

f E and F through line 227 containing valve 22.8, line 229 containingvalve 230, line`231 containing valve 232, line 233 containing valve 234,line 23S containing valve 236 and line 237 containing valve 238,respectively. The flue `gas which is discharged through the lines justmentioned,

v enters a common header 240 which in turn is -connected gasf In thisexample, the hydrogen containing gas which is supplied through commonheader 16, is passed upward- 1y through line 242 containing valve 243,and thence, it

enters the bottom of reactor F via header 57. The hydrogen purge gas isdischarged from reactor F through a line 84 containing valve `89, afterwhich it flows into the header70. Likewise, the hydrogen purge ofreactors A,

` B, C, D and Eis effected by passing hydrogen gas through line 249containing valve 250, line 251 containing valve 252,.line 253containingvalve 254, line 255 containing valve 256 and line 257containing valve 258, respectively. Similarly, the hydrogen purge gas isdischarged from rev actors A, B, C, D and E through `line 68 lcontainingvalve 69,1 line 81 containing valve S6, -line 82 contain-ing valve 87,line 73 containing valve 74 and line S3 containing FIGURBSS and 4illustrate 'the V.processing cycles for the -unit shown in FIGURES' 2and 2A.

IHaving thus supplied a description of our invention by means ofspecific examples thereof, Vit should tbe under'- stood that no unduelimitations or restrictions are to be imposed by reason thereof, butthat the vscope of Ithe present invention is defined by the appendedclaims.

We claim:

'1. A process for converting a residual oil obtained from a vacuumdistillation having a gravity lless than 20 A.P.l. and a carbon residuegreater than about 0.6 percent by weight to a gas oil product and aheavier asphalt product which comprises contacting said residual oilwith a catalyst consisting of a nickel oxide and tungsten oxidesupported on alumina at a temperature of 750 to about 850 F., a pressurebetween about 500 and about 1500 p.s.i.\g., in the presence of Aaddedhydrogen in the amount between about 2500 and about 30,000 s.c.f.b.,controlling the severity factor of the reaction between about 0.09 'andabout 0.50 and recycling the asphalt product to the reaction zone.

2. A process which comprises converting a residual oil obtained from avacuum distillation having a gravity less than about 13 and a carbonresidue of about 5 to about 30 percent by weight to a gas oil productand an asphalt product by contacting said residual oil with anickel-tungsten-alumina catalyst at a temperature between about 750 and`about 850 F., a pressure between about `500 and about 1500 psig., aseverity factor between about `0.09 and about 0.50 in the presence ofadded hydrogen, said conditions being selected to provide between aboutand about 70 percent of asphalt product and recycling the asphaltproduct to the reaction zone.

3. A process which comprises subjecting a crude oil to an atmospherictopping operation whereby a gas oil Y fraction and a reduced crudefraction including gas oil valve 88, respectively., The hydrogen purgeis conducted with 670,000 s.c.f.h. of gas, at a temperature of 880 F.

and a pressure of 900-p.s.i. g. k

Following the purge with hydrogen containing gas, the' V reactor'isdepressurized. At the appropriate time in the cycle,-the gaseousmaterial in reactor A, B, C, D, E or F is Vented through line 260, i262,264, 266, 268` or 245, respectively, and thence, it flows to yailarevialine 247. Further, after upiiow regeneration, the particular reactor lis'purged with steam, and then repressured by means of 21,150 pounds perhour, and it is transported to distributor 282, within the tower, bymeans of a pump 283 and a line 284 connected therewith. Y The hot fluegas is charged to the tower at a temperature and a rate suiicient tovaporize substantially all of the water which is introduced into thebottompart of tower 280. The heat requires to vaporize the water servesto cool the hue gas. v Flue gas containing water vapor is `dischargedoverhead fromy tower -280 by means of a line 286. The cooled liuc gas iscornpressed byk means of compressor `280, and thence, it hows into lline178 which in turn is connected to line 177 in A which regeneration airis flowing to produce anV oxygen containing gas at 800 F.

are separated therefrom, subjecting the reduced crude fraction lto adistillation treatment under Vacuum thus producing a second fraction ofgas oil and a vacuum tar having an A.P.I. gravity less than about 20,subjecting the vacuum tar to contact with a catalyst consisting of anickel oxide and tungsten oxide supported on alumina at a temperaturebetween about 675o and about 925 F., a pressure between about 500 andabout 1500 p.s.i.g., a severity factor of between about 0.09 and about0.50, in the presence of added hydrogen in the amount between about 500and about 50,000 s.c.t`.b., thus producing a mixture comprising gas oil:and asphalt passing the mixture comprising Ygas oil and asphalt to theaforesaid atmospheric topping step for separation, separating theasphalt `from the gas oil and passing the asphalt with the vacuum tar tothe catalyst treating step.

4. A process which comprises subjecting a crude oil including naphtha,gas oil'and reduced crude to an atmospheric topping operation wherebysaid fractions are produced, subjecting the naphtha to contact with asuitable reforming catalyst under reforming conditions to obtain -a net.production of hydrogen and a reformed liquid product, subjectingV thereduced crude to a distillation treatment under vacuum to produce asecond gas oil fraction and a vacuum tar, subjecting the vacuum tar yhaving an A.P.I. gravity less than 20 and la carbon residue greater thanabout 0.6 percent by weight to contact with a catalyst consisting ofnickel-tungsten and alumina at -a temperature between about 675 andabout 925 F., a pressure less than 2,000 p.s.i.g., a severity factorbetween about 0.09 and about 0.50in the presence of hydrogen obtainedfrom said reforming step in an amount between about 500 and about 50,000s.c.f.b., thus `producing a gasoil product andan 4asphalt product andpassing said .gas oil product and said asphaltiproducty to said toppingoperation.

5. A process for converting a residual oil obtained from a vacuumdistillation having a gravity lessthan 20 A.P.I. to la gas oil productand a heavier asphalt product which comprises contacting said residualoil with a nickeltungsten-alumina catalyst at a temperature betweenabout 675 and about 925 F., a pressure less than 2000 p.s.i.g., aseverity factor between about 0.09 and about 0.50 in the presence ofadded hydrogen, and recycling the asphalt product to the reaction zone.

2,367,527 Ridgway Ian. 16, 1945 14 Horne et a1. Aug. 1, 1950 FlemingFeb. 13, 1951 Wilson Feb. 13, 1951 Douce J-uly 3, 1951 Fleming Nov. 25,1952 Lanning Feb. 3, 1953 Engel Sept. 1, 1953 Anhorn et Aa1 Jan. 18,1955 Knox Ian. 25, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION VPatent N0 39043D 769 July 10V 1962 Marvin F., Nathan et aluIt is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column l, line 16., after U'catalyticH insert cracking column 2v line.BOq for "usmallly" read usually column 4, line l3 for "0o 1" read O1"-g line I21e for "'decreases" read decrease column 1lv line o8v for"requires" read required Signed and sealed this 30th day of Octobexh1962.Il

(SEAL) Attest:

ERNEST w. swlDER DAVID L. LADD Attesting Officer Commissioner of Patents

1. A PROCESS FOR CONVERTING A RESIDUAL OIL OBTAINED FROM A VACUUMDISTILLATION HAVING A GRAVITY LESS THAN 20* A.P.I. AND A CARBON RESIDUEGREATER THAN ABOUT 0.6 PERCENT BY WEIGHT TO A GAS OIL PRODUCT AND AHEAVIER ASPHALT PRODUCT WHICH COMPRISES CONTACTING SAID RESIDUAL OILWITH A CATALYST CONSISTING OF A NICKEL OXIDE AND TUNGSTEN OXIDESUPPORTED ON ALUMINA AT A TEMPERATURE OF 750* TO ABOUT 850* F., APRESSURE BETWEEN ABOUT 500 AND ABOUT 1500 P.S.I.G., IN THE PRESSURE OFADDED HYDROGEN IN THE AMOUNT BETWEEN ABOUT 2500 AND ABOUT 30,000S.C.F.B., CONTROLLING THE SEVERITY FACTOR OF THE REACTION BETWEEN ABOUT0.09 AND ABOUT 0.50 AND RECYCLING THE ASPHALT PRODUCT TO THE REACTIONZONE.